Vision enhancing systems for a low vision individuals have made significant advances in the past few years. As shown by U.S. Pat. Nos. 4,704,000 and 5,680,195, vision enhancing system now may be provided that are light enough to be mounted on eyeglasses. And as shown in an article by Goldberg in Electronic Design, Apr. 14, 1997, entitled "Self-Focusing Infrared Telescope Glasses May Restore Sight to Millions", such low vision systems may include auto focusing While enormous strides have been made, it is desirable to provide an optical system for low vision individuals that is even lighter, and has more effective and efficient focusing, and that is well suited for auto-focusing such as discussed in the Goldberg article.
One of the key features of the present invention that allows a lightweight, efficient, and effective, system is the provision of a mirror cluster. Two mirrors are provided mounted in the cluster at an angle of about 90.degree. to each other, and for substantially linear movement. This arrangement of the mirrors provides two units of focus for every one unit of travel, making focusing quicker and easier. While the same basic results could be achieved by moving prisms instead of mirrors, mirrors are much lighter in weight than prisms and therefore are much more suitable to low vision systems, particularly those that must be light enough to be mounted on eyeglasses.
According to one aspect of the present invention, a vision enhancing optical system is provided comprising the following components: An objective lens. An eyepiece lens. A mirror cluster comprising first and second substantially planar mirrors which are disposed at an angle of substantially 90.degree. with respect to each other. And, the mirror cluster mounted for movement in a substantially linear path with respect to the objective and eyepiece lenses. The objective and eyepiece lenses may be mounted on substantially parallel lines of sight, in which case the mirror cluster substantially linear path of movement is substantially transverse to the lines of sight.
The optical system of the invention preferably further comprises a third mirror disposed optically closer to the objective lens than the eyepiece lens; and a fourth mirror for directing light reflected by the mirror cluster to the eyepiece lens. Preferably the above-recited optical components comprise a first set, and the system further comprises a second set of optical components including an eyepiece, lens and four mirrors substantially identical to the optical components of the first set, the mirror cluster of the second set facing (or facing away from) the mirror cluster of the first set, and wherein the first and second sets comprise a binocular system.
In binocular systems, the pupillary distance (that is how far apart an individual's pupils are) must be accommodated. This can be accommodated by allowing decoupling of various components in the system of the invention, and reattachment once adjusted. An easy to adjust (but also easy to move out of adjustment) mechanism for this purpose such as found in conventional binoculars is not necessary because the system of the invention will not be normally be used by more than one or a few people.
Binocular systems also need to ensure "convergence". When an object to be viewed is from about three feet (one meter) to about ten-twelve inches (30 cm) from the objective lens or lenses of a binocular system, unless some adjustment of the optical components is effected, it is not possible to maintain a fused binocular image. Convergence is provided according to the invention by mounting each third mirror pivotally, for pivotal movement about a pivot axis substantially perpendicular to the substantially linear path of movement of the mirror cluster. Preferably means are provided for automatically pivoting each third mirror in response to movement of the mirror cluster to maintain a substantially constant optical relationship between the mirror cluster and the third mirror, and to provide a fused binocular image for objects about one meter or less from the system.
The automatic pivoting means may comprise any conventional structure which effects pivotal movement of one component to which it is connected while allowing relative linear movement of that component with respect to another. In the preferred embodiment according to the invention the automatic pivoting means comprises a cam, a cam follower, and a link connecting the cam follower to the third mirror, the link including a slip joint allowing relative linear movement between the third mirror and the mirror cluster while translating movement of the cam follower to pivotal movement of the third mirror. Alternatively the means for automatically pivoting may comprise a link connected to the mirror cluster, and an arm having a lost motion connection to the third mirror. [An adjustment mechanism connecting the link to the arm may also be provided to accommodate different pupillary distances.] In any event, pivoting action is initiated only when--as perhaps sensed by the position of the self-focusing mechanism--the object to be viewed is about one meter away.
In the preferred embodiment the third and fourth mirrors are substantially perpendicular to each other, and the first and second mirrors are substantially perpendicular to each other, and the fourth mirror is substantially parallel to the second mirror.
A number of different housing arrangements may be provided for the optical components. For example the third mirrors of the first and second sets may be mounted in a first housing, with the mirror cluster, eyepiece lens, and fourth mirror of the first and second sets, respectively, mounted in second and third housings, respectively. The objective lens may be operatively mounted with the first housing and comprise a common objective lens to both the first and second sets of optical components, or the second set of optical components may include its own objective lens, with the optical components of the first set mounted in a first housing and those of the second set mounted in a second housing.
According to another aspect of the present invention an optical system is provided comprising the following components: A mirror cluster comprising first and second substantially planar mirrors disposed at an angle of substantially 90.degree. with respect to each other. The mirror cluster mounted for movement in a substantially linear path. And, a third mirror disposed for optical cooperation with the first mirror, the third mirror generally parallel to the first mirror, and pivotal about an axis substantially perpendicular to the substantially linear path. The system typically also further comprises a fourth mirror substantially parallel to the second mirror, and optically cooperating with the second mirror, the third and fourth mirrors substantially perpendicular to each other and the first and second mirrors substantially perpendicular to each other.
Preferably the above recited optical components comprise a first set, and the system further comprises a second set substantially identical to the first set, and means are provided for pivoting the third mirror of each set about a pivot access in response to movement of the mirror cluster in the substantially linear direction, to ensure substantially effective convergence, i.e. so that a fused binocular image is maintained even when the object to be viewed is close to the objective lens or lenses (e.g. a meter or closer). The means for automatically pivoting the third mirror may be as described above, as may the other components as set forth above.
The system is preferably mounted on a pair of eyeglasses, and a motorized system for auto-focusing may be provided for moving the mirror cluster. For example the mirror cluster may be mounted for movement by a traveling nut, and a threaded rotatable shaft parallel to the linear movement of the mirror cluster, rotation of the shaft (such is powered by a small motor) may effect substantially linear movement of the mirror cluster.
It is the primary object of the present invention to provide a lightweight, efficiently, universally, and effectively focusable, optical system for use by low visions persons, such as in association with eyeglasses. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.